MIPS: uprobes: remove incorrect set_orig_insn

commit ddabfa5c upstream.

Generic kernel code implements a weak version of set_orig_insn that
moves cached 'insn' from arch_uprobe to the original code location when
the trap is removed.
MIPS variant used arch_uprobe->orig_inst which was never initialised
properly, so this code only inserted a nop instead of the original
instruction. With that change orig_inst can also be safely removed.
Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Fixes: 40e084a5 ('MIPS: Add uprobes support.')
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14299/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/mips/include/asm/uprobes.h

@@ -36,7 +36,6 @@ struct arch_uprobe {
 	unsigned long	resume_epc;
 	u32	insn[2];
 	u32	ixol[2];
-	union	mips_instruction orig_inst[MAX_UINSN_BYTES / 4];
 };
 
 struct arch_uprobe_task {

arch/mips/kernel/uprobes.c

@@ -280,24 +280,6 @@ int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm,
 	return uprobe_write_opcode(mm, vaddr, UPROBE_SWBP_INSN);
 }
 
-/**
- * set_orig_insn - Restore the original instruction.
- * @mm: the probed process address space.
- * @auprobe: arch specific probepoint information.
- * @vaddr: the virtual address to insert the opcode.
- *
- * For mm @mm, restore the original opcode (opcode) at @vaddr.
- * Return 0 (success) or a negative errno.
- *
- * This overrides the weak version in kernel/events/uprobes.c.
- */
-int set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
-		 unsigned long vaddr)
-{
-	return uprobe_write_opcode(mm, vaddr,
-			*(uprobe_opcode_t *)&auprobe->orig_inst[0].word);
-}
-
 void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
 				  void *src, unsigned long len)
 {